1. Field of the Invention
The present invention pertains generally to lubrication of specified substrates and, more particularly, to an improved lubrication composition and method of its application. The improved, wear-resistant, low friction substrates have a coating provided by such composition, said substrates including sound and video recordings such as gramophone or phonographic records, video discs and the like.
2. Description of the Prior Art
Lubrication of various substrates, and particularly of substrates upon which recorded signals have been stored and from which said signals can be recalled by dynamic means, has not been generally recognized and where attempts have been made to lubricate such substrates they have not proven fully satisfactory. In particular, substrates possessing this special problem include synthetic, natural and combinations of thermoplastic materials and include resins, shellac, polyvinyl acetate, polyvinyl chloride, cellulose acetate, cellulose nitrate and their derivatives as well as numerous other compositions that are generally formed through various press moulding means into photographic records or discs as well as similar thermoplastic structures having trackable groove contours and reproducing recorded monaural and stereophonic and video signals therefrom.
As is generally known, a phonograph cartridge serves to convert the variations on the walls of the grooves of a phonograph record into electrical signals whereby the variations or wavy pattern on the grooves determine the frequency and the amplitude of the sound vibrations. The cartridge includes a stylus or pickup needle usually in the form of a diamond of sapphire which generally has a hemispherical or ellipsoidal tip which rides or dips into the record groove and moves in response to variations of the pattern of said groove. The stylus, in turn, is generally attached to an armature which moves with the stylus to induce variations in an electrical or magnetic field in response to the stylus movement. This generates an electrical signal representative of the groove configuration which may then be amplified and used to drive speakers. Again, the stylus is caused to mechanically vibrate in response to the variations in amplitude and frequency of the undulations of the record groove wall which comprise the recorded signal.
A stylus has to track a plurality of evenly spaced groove contours with recorded signals on the order of between 15-20 and 20,000 Hz. Moreover, with the introduction of discrete four-channel record systems or quadrasonic systems, a stylus must faithfully track grooves with recorded signals to cause vibrations of up to 50,000 Hz. As the stylus rides in the record groove, the relatively hard stylus wears away the relatively soft thermoplastic material of the record forming the groove. There has been heretofore no easy solution to alleviate the problem of record wear caused by the stylus riding in the groove contour of such recordings.
The deterioration of the sound quality of records with increase in the number of plays through wear of their tracks by repeated uses results in records becoming unusable and often being discarded within a short period of time. A number of factors are responsible for wear including the general wear through abrasive and adhesive wear mechanisms to an extent proportional to stylus loading. This loading is not only the deadweight stylus load on the record which may range from about 1 gram to 4 grams but also includes dynamic inertial forces caused by stylus mass and the frequency of stylus directional changes as it tracks the groove undulations. As known, reduction of deadweight load and stylus mass lowers the rate of groove wear but wear and the consequent loss of playback fidelity cannot be entirely eliminated. At any rate, most attempts of the prior art via record cleaners or alleged lubricates have simply resulted in cleaning only or depositing chemical films onto records without being successful in that such materials generally reduce the record fidelity due to rapid groove wear if cleaned or to hydrodynamic damping of the stylus tracking if oily substances are deposited. Further, it is often observed in the use of these materials that the noise level is increased due mainly to dust captured along with the formation of a tacky deposit upon the stylus. Moreover, it has been observed that attempts to use powdered solid lubricants such as graphite, molybdenum disulfide and the like have several disadvantages for they do not only reduce fidelity but also increase noise due to particulate interference in the record grooves.
In general, various silicones and hydrocarbon waxes and certain fluorinated telomeric compositions have been used as lubricants in sundry applications. U.S. Pat. Nos. 3,067,262 and 3,345,424 discuss the manufacture of such fluorinated telomers. U.S. Pat. No. 3,067,262 discloses tetrafluoroethylene telomerized with trichlorotrifluoroethane whereby moderately high molecular weight products are produced. The patent discloses further that in order to obtain a wax-like product, a second active telogen must be included in the telomerization process. In general, such active telogens are hydrogen-containing compounds including tertiary hydrocarbons, aliphatic alcohols, divalent sulfur compounds, aliphatic tertiary amines, aliphatic ethers, carbonyl compounds and dialkyl phosphites. Since these active telogens contain hydrogen, the telomer products contain significant amounts of hydrogen, e.g., from 0.05 to 2% by weight.
U.S Pat. No. 3,345,424 discloses an improvement over the telomeric compositions of U.S. Pat. No. 3,067,262 in that the improved compositions have no hydrogen and are of a lower melting point. In effect, the improved compositions are derived from the products obtained by telomerization of tetrafluoroethylene with certain haloalkanes. In fact, the compositions are made by the chlorination or fluorination of certain fractions of telomer iodide mixtures whereby the iodine is replaced by chlorine or fluorine. The utility of these compositions is found in their application as a general dry lubricant, protective surface treatment, oil and water repellents, and a mold release and antistick composition.
In U.S. Pat. No. 3,652,314 to Castner, a method is disclosed for renewing, resurfacing and preserving a phonograph record by the steps of coating the record with a composition consisting essentially of acrylic polymer, polyethylene emulsion, a detergent, an ether and water, brushing the composition into the grooves, removing any excess, drying and playing the phonograph record.
In U.S. Pat. Nos. 3,862,860 and 3,954,637, a method and composition are disclosed for improving lubricity, abrasion resistance, and lowering the coefficient friction of substrates such as photographic films, magnetic surfaces and other recording elements by applying to such substrates a solution comprising tetrafluoroethylene telomer and a copolymer of vinyl chloride and trifluorochloroethylene in a volatile solvent, drying and removing the excess, and substrates so lubricated. In effect it was shown that the combination of a lubricant, viz., tetrafluoroethylene telomer and non-lubricant, viz., poly(trifluorochloroethylene-co-vinyl chloride) provides a coefficient of friction below that of the lubricant per se.